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No. 607,239. Patented July l2,'l898.

. L. W. HILD'BURGH.

TELEGRAPH.

(Application filed June 2, 1897.)

(no Model.) I j a Sheets-Sheet 1.

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No. 607,239. Patented July I2, I898.

L. w. HILDBURGH.

TELEGRAPH.

(Application filed June 2, 1897. (No Model.) 3 Shouts-Sheet 2.

XOM Z M 4 dwmwee rm: NQRRIS PETERS cu, FNOTD-LITHO., wAsumcTuN. n. c

No. 607,239. Patented luly l2, I898. L. W. H ILDBUBGH. TEE EGRAPH.

(Application filed June 2, 1897.) (No Mode!.) 7 3 SheetsSheat 3.

UNITED MES LEO WALTER HILDBURGH, onivEw YORK, N. Y.

TELEGRAPH.

SPECIFICATION forming part of Letters Patent No. 607,239, dated July 12, 1898.

Application filed June 2,1897. Serial No. 639,189. (No model.)

To all whom it may concern.-

Be it known that I, LEO WALTER I'IILD- BURGH, a citizen of the .United States, residing at New Yorkcity, in the county and State of New York, have invented a certain new and useful Improvement in Telegraphs, of which the following is a specification.

The object of my invention is to apply the principle of the separation of the positive and negative waves of an alternating current to harmonic telegraph systems.

In my Patent No. 571,948, issued November 24., 1896, I described a system of telegraphy in which alternating currents were employed for the simultaneous transmission of two or more messages in the same or opposite directions by separating the positive and negative waves, and each set of waves being employed for transmitting and receiving messages. My present system depends upon the separate control of the plus and minus waves of various frequencies admitted to the line in order that each set of waves shall affect only its own instruments.

In the accompanying drawings I have illustrated my invention in several forms.

Figure 1 is a diagram illustrating two transmitting-stations A and B and two receivingstations 0 and D. In this illustration, for the purpose of avoiding repetition, I have shown the transmitting-stations of different forms. Fig. 2 is a diagram illustrating transmitting and receiving instruments at each end of the line, the generators being arranged in series. Fig. 3 is a diagram similar to Fig. 2, but showing the generators connected in parallel. Fig. at is a diagram illustrating a receivingstation at which the instruments are arranged in two groups, one group comprising the instruments affected by positive impulses only and the other group comprising the instruments affected'by negative impulses, and a device for each group controlling the passage of the impulses. Thus a single device controls the passage of the impulses to all the receiving instruments of one group instead of employing such a device for each receiving instrument. Fig. 5 illustrates a method of receiving byelectrical resonance, the instruments being connected in parallel. Fig. 6 illustrates a modification of the arrangement of Fig. 5 and applied to the receiving system of Fig. l. Fig. 7 illustrates a system employing resonant transmitters and resonant receivers. Fig. 8 illustrates the application of my invention to a telephone system, and Fig. 9 illustrates a form of commutator which may be employed with the transmitters to control the passage of the positive and negative impulses to the line.

Referring to Fig. 1, A and B indicate two sets of transmitting instruments or stations, and O and D indicate two sets of receiving instruments or stations. At the transmittingstations G and G represent alternating-cur rent generators connected in series in the main line L and whose pulsations are of dif ferent frequency. The transmitting instruments are located in branches connected across the terminals of the generators, and these branches contain devices for controlling the passage of the positive and negative impulses to the line. By this arrangement when the transmitting instrument--a key, for instance-in one branch is closed one set of impulses will be short-circuited and the other set will pass to the line. At station A one device is employed for controlling the passage of the positive and negative impulses to the line, while at station B such a device is placed in each branch. These devices may be asymmetrical resistances or equivalent means. The circuit connections at station A are as follows: from line L by wire a to key T, contact and wire 1 to device S, wire 8, contacts 5, and wire 7, through resistance X and wire a. to the line. This branch will hereinafter be referred to as branch T, and it will be assumed that the closure of key T short-circuits the positive impulses, and the negative impulses pass to the line unaffected by the closure of that key. When key T is opened again, the positive impulses will again pass to the line, and thus in operating that key the positive impulses alternately pass to the line and around the branch T, the effect being equivalent to the opening and closing of a key in a simple telegraplnline. The circuit connections to the other branch at station A are as follows: from line L by wire a to key .T', contact and wire 2 to device S, wire 4, contacts G, and wire 8, through resistanceX and wire a to the line. This branch, hereinafter referred to as branch T, it will be assumed, controls the passage of' the negative impulses to the line, and the action will be the same as with branch T. The resistance X is provided for the purpose of preventing injury to the generators upon closing the branches T or T. If, for instance, the device S at station A is an asymmetric resistance, which permits positive impulses to pass through it in one direction and negative impulses in the opposite direction, it will be seen that the closure of key T will permit the positive impulses from the generator G to pass through the branch T and the device S to the other termin al of the generator, hence short-circuiting the positive impulses from the line, while the negative impulses pass to the line unalfccted. If the key T be closed, it will be seen that the negative impulses will pass through the loop T and the device S and be short-cireuited from the line, and the positive impulses will be unaffected and pass to the line. At station l the same effect is produced. At this station, however, two independent branches are connected across the terminals of the generator G. One branch contains a resistance X, device S, and transmitter T The other branch contains a resistance X, device S and transmitter T The devices S and 5 1113,) be similar to the device Sthat is, assymmetrical resistances or equivalent meansand the device 8 is designed to permit the posi* tive impulses to pass around the branch T while the device is designed to permit the negative impulses to pass through the branch T Thus the closing and opening of the branches T and T short-oircuit,respectively, the positive and negative impulses from the line, the effect being, as before stated, the same as at station A. With either of the arrangements just described it will be seen that four messages maybe transmitted over the line simultaneously and withoutinterference, since the two sets of positive impulses will be of different fregprcncy and the two sets of negative impulses will be of different fre quency.

The receiving instruments in Fig. l. are placed at two stations 0 D, and the instruments at each station are placed in two branches of the main line, (marked 0 c atstatien C and (Z cl at station D.) The branches 0 and (Z contain devices S for permitting the passage of the positive impulses from the transmitting-stations, and branches 0 and (1 contain devices S for pcrmittingthc passage of the negative impulses only. The receiving instruments are indicated at R. It will be noticed that I have shown three receiving instruments at the station 0 and but one receiving instrument at station I). This is done simply to show the flexibility of the system, since it will be understood that one of the receivers in the branch 0 may be placed in the branch (Z or there may be a greater number of receivers, and it will be understood that senses the location and grouping of the receivers, as well as the transmitters, will of course be such as will meet the demands of the system.

In Fig. 2 I have illustrated two sets of transmitters at each end of the line and aset of receivers at each end. The generators G, G, G and G" are in series, and the eight trausmitting instruments T to T are placed in. branches around the terminals of the generators, as at station ll of Fig. 1. The receiving instruments are connected in parallel, four at each end of the line, and each receiver is provided with a device S or 55" to control the passage of the proper impulses to the re ceivers It.

In Fig. 3 the generators G, G, l and 1 are connected in parallel across the line L'l'i, and with each generator are connected two branches containing devices it and 52% and transmitting instruments T to T inclusive. The receiving instruments are cmincctcd in parallel across the line, each receiver being in series with a device ill or F5, as in Fig. In this illustration each branch. from the generator is normally open, and the respective generators are thus disconncctm'i from the line, so that the operation of the trans mitter does not short-circuit any set of impulses, as in the arrangements of lligs. l. and 2. The devices is" permit the pass go of the positive impulses through their respective branches, and the devices f5 control the passsage of the negative impulses through their respective branches. 'il 'ith this arrangement it may be necessary to provide each transmitting-circuit with a device at at, which will permit only a current of a certain frequency to ilow on that circuit, whereby the passa e of the impulses from one generator thron either of the other generator or transmitter circuits will be prevented.

In Fig. l- I have illustrated two groups of receivers It and R,one groupthose designed to be affected by the positive i1npulses bcing connected between the branch conductor it and the rcturn-circuit ll of the main line, and the other group-those designed to be affected by the negative impulses being connected between the branch conductcjlr ID and the returu-conduetor l). The branch con ductor F contains a device for permitting the passage of the positive impulses only to the group of receivers It, and the branch conductor l9 contains the device 53 for pcrmitting the passage of the negative iin ulses only to the group of receivers it. if addi tional receiving instruments are required, they may be connected between the branch conductors It It and the conrfliurtor l1 or they maybe connected directly across the main line l It, as indicated in dotted lines. The

arrangement of receivers illustrated in this figure may be applied to the systems of Figs. 1, 2, and 3, the receivers being all connected as indicated in. Fig. l or ntrtly munccted as in the other ligu res and partly con nected as in Fig. .1-.

lit") resonance.

In Fig. 5 I have illustrated the receiving instruments arranged to operate by electrical S and S indicate the devices for controlling the passage of the positive and negative impulses, respectively. the receiving instruments. In series with these instruments are connected the con densers F and any suitable form of inductance V F, the functions of which are well understood.

In Fig. 6 I have shown a modified arrangement of the receivers operating by electrical resonance applied to the receiving systems of Fig. 4. In this illustration E and E are the two branch conductors, as in Fig. 4:, and S and S are the devices for controlling the passage of the positive and negative impulses,respectively. R indicates the receivers connected between the branch conductor E and the main-line conductor L, and R inclicates the receivers connected between the branch conductor E and the main conductor L. The condensers are shown at F and the inductance at F.

In Fig. 7 is shown a system employing both resonant transmitting and receiving instru ments. Three generators G, G, and G are shown connected in series and each of different frequency. Six transmitter-circuits are shown, and each is provided with means for adjusting for inductance and capacity. The transmitting instruments are illustrated as keys T to T The transmitter-circuits T and T are provided with devices S for permittin g the flow of positive impulses from the generators G and G, respectively, and the closure of those keys short-circuits from the main line the two sets of positive impulses from the generators G and G. Transmittercircuits T and T are provided with a single device S for permitting the flow of negative impulses from generators G and G, and the closure of those keys short-circuits from the main line the two sets of negative impulses from the generators G and G. Separate devices S may be employed for the circuits T and T, if desired, a single device being shown in this instance merely to illustrate another way of connecting the instruments. Another way of connecting the transmitters is shown at transmitter-circuitsT and T, where separate devices S and S are employed for controlling the passage of the impulses, circuit T receiving the positive impulses and circuit T receiving the negative impulses. Transmitters T and T control, respectively, the flow to the main line of the positive and negative impulses from generator 1 R to R represent resonant receiviug instruments. Instruments R and R are shown connected in separate receiving-circuits and provided, respectively, with devices S and S for permitting the flow of positive and negative impulses from generator G and which impulses arecontrolled, respectively, by transmitters T and T Receiving instruments R and R receive the positive impulses of different frequency from R indicate the two generators G and G, controlled by transmitters T and T A single device S is shown for controlling the flow of the positive impulses to receivers R and R although one of these devices may be employed for each receiver. Receivers R and R are connected in the same manner as receivers R and It", and a single device S is shown for controlling the flow of the negative impulses of different frequency from the generators G and G, controlled by transmitters T and T.

In the telegraph system the device for controlling the passage of the positive and negative impulses to the main line may be a mechanical device-such, for instance, as the commutator illustrated in Fig. 9. In this illustration L and L indicate the main line. H and II may be the collecting-rings of a generator, and I represents the generatorwinding. The collecting-rings may be carried by the armature-shaft or by a separate shaft geared to the armature-shaft, and in either case the ring II will be made adj ustable on the shaft, in order to adjust for changes in the phase of the current from generator I. Ring H has a continuous contact-surface, while ring H is notched at both ends, a' section of insulation being inserted at the notches, so that metal surfaces 72. and insulating-surface 7b will alternate, as shown. The generator-winding is connected to the rings II and II. with ring H, from which extends the main line L. A brush I makes contact with the continuous metal surface of ring H, to which brush the other 'main conductor L is connected through a resistance Y. The transmitting instruments or keys are shown at T and T which are connected to the main line L by wires 14 and 15, respectively. The main circuit is always closed from the main line L through brush I, ring II, generator-coils I, ring H, brush I to main L, through resistance Y. The operation of the transmitters T and T produces the same results as the operation of transmitters T and T of Fig. 1.

The path of the current when both keys are open is from line L to brush I, ring II, generator-coils I, commutator II, and from commutator II the current passes to line L through two parallel circuits, one including brush I and resistance 'Y and the other including brush I, Wire 16, contacts 18, and wire 20 at one instant and at the next instant brush 1 wire 17, contact-s l9, and wire 21, due to the alternate makes and breaks at brushes 1 and I". Contacts 18 and 19 are spring-contacts, which are held closed by the insulated rear ends of the keys and which contacts will open when the keys are closed. If key T affects the positive impulses and T the negative impulses, the path of the impulses when the keys are closed will be as fol lows: \Vhen key T is closed, the path of the line-current at one instant will be line L, brush 1', ring II, generator-coils I, ring H, and in parallel through brush I and resist A brush I makes contact IIO 4 comes ance Y, and brush 1", wire 17, contacts 19, wire 21, line L. The next instant the path of the line-current will be line L, wire 1 1, key T, resistance Z, wire 16, brush 1, ring II, brush I resistance Y, line L. The posi tive impulses will be shortcircuited by key T, and at those instants the line-current will divide between the generator-coils and the circuit, including wire 1-1, key T resistance Z, wire it, brush 1'; but the line-resistance will not change, because the resistance of Y will make the total resistance from line L to L when Z and I are in parallel and Y in series the same as the resistance of coils I alone. \Vhen key T is closed, the path of the lineon rrent at one instant will be main line, brush 1, ring ll, generator-coils l, ring 11, and in parallel through brush P and resistance Y, and brush 1, wire 10, contacts 18, wire 20, line L. The next instant the path of the lineeurrent will be line L, wire 15, key T, resistance Z, wire 17, brush 1, ring ll, brush 1*, resistance Y, line L. The negative impulses will be short-eircuited by key T and theel't'cct will be similar to that produced by the operation of key T. \Vhen both keys are closed, the generator-waves will be continuously shut out from the circuit. Thus by the arrangement of Fig. 9 the main line is never opened the resistance is maintained constant, and the positive and negative impulses from the generator may be short-circuited from the line at will.

In the telephone system illustrated in Fig. 8 I have shown four telephone sets or stations A, B, C, and D. These sets comprise, respectively, local transmitter-circuits L L", L, and L local reeeiver-circuits Ii, L L and L, and local circuits containing asymmetrical resistances or equivalent devices 8, S, i and S for short-circuiting either the positive or the negative waves of the alternating current produced by induction-coils 11s, and each oi the lastnamed local circuits is provided with a i'eversirlgswiteh, so that the connections of the devices S", the. may be reversed and control the passage of either the positive or the negative waves over the main line. The localreceiver-circuitsarearranged in two branches, in either of which branches the receivers 1-1, R R and :t may be connected. The receiver branches are provided with devices S and foreontrolling, respectively, the passage of the positive and negative waves.

\Vith the connections as in Fig. 8 station A may communicate with station 0 and station 13 may connnunicate with station D. then the transmitting-diaphragm at station A is vibrated, the negative waves of the alternating current from the induction-coil will llow around the local circuit containing asymmetrical resistance S and the positive waves will llow through the branch of the local circuit L containing the device S, which device allows the positive waves from transmitter L to pass thron gh. receiver Rf and along the line and through the branch of the local, circuit L" containing device i", and then along the line to receiver R at station. U. The same action takes place at station 15 when the diaphragm in local circuit L is vibrated, except that the switch in the local circuit containing device S is reversed and the positive waves will flow around that local circuit and the negative waves pass over the line to receiver R, the path being through the branches of the local. receiver-circu its L L and L containing devices 5*, which permit only nega tive waves to llow in those circuits. The switches .in the local circuits containing devices S and S" at stations U and l) are adjusted so that the positive and negative waves from the transmitter-circuits L and L, re spectively, will pass over the line, and these waves will affect the distant receivers it and R respectively. Ifstation A desires to comlnunicate with station l3, receiver it" is con-- nected in the other branch of the local re ceiver circuit L and the reversing-switch for device 6 is shifted so that the positive waves from station A. will be shortcircuited from the line. The connections at other stations will be similarly changed to communicate with different stations, and thus it will be seen that any pair of stations may communieate with each other without interference.

The telephone system may be extended to include a greater number of stations by applying arrangements similar to those em ployed in connection with the herein-described telegraphsystemsemploying resonant circuits.

The devices employed for controlling the llow of the positive and negative waves to the line may be arranged to short-circuit all the waves of one set from the line when the transmitting instruments are operated, or such de vices may be arranged to only partially shortcircuit the waves of one set from the line, without departing from the spirit of my invention.

XV hat I claim is- 1. Ina system of electricalcommunication, the col'nbination with a main line and a son rre of alternating current therefor, of means for controlling the flow of the positive and negative impulses from the generator by shortcircuiting one set of impulses at the time of generation of either set of waves, the otherset being unaffected, substantially as set forth.

2. In a system of electrical communieation, the combination with a main line and a source of alternating current therefor, of means for controlling the llow of the positive and negative impulses from the generator, said means being located at or near the generator, and means for maintaining the line resistance, substantially as set forth.

In a system of electrical communieaticm, the combination with a main line, of two or more generators generating alternatin cur rents of different frequencies, two branch cir cuits connected across the terminals of each generator, transmitting instruments located in each branch, and means for separately controlling the fiow of the positive and negative impulses from each generator over the line to receiving instru n1 ents, substantially as setforth.

4. In a system of electrical communication, the combination with a main line, of two or more generators generating alternating currents of different frequencies, two branch circuits connected across the terminals of each generator, transmitting instruments located in each branch, and a device in each branch for causing a set of impulses of one sign to pass over the branch in which such device is located when the transmitting instrument is closed, thereby -short-circuiting that set of impulses from the line, substantially as set forth.

5. In a system of electrical communication, the combination with a main line and a source of alternating current therefor, of a device combined with transmitting instruments for controlling the flow of the positive and negative impulses from the generator over the main line by causing one set of impulses to flow through a branch circuit, the other set being unaffected and allowed to pass over the main line, substantially as set forth.

6. In a system of harmonic telegraphy, the combination with a mainline, of two or more generators generating alternating currents of different frequencies, transmitting instruments for controlling the flow of the positive and negative impulses over the line, each transmitting instrument being arranged to short-circuit the impulses of a given sign and frequency, substantially as set forth.

7. In. a system of harmonic telegraphy, the combination with a main line, of two or more generators generating alternating currents of different frequencies, transmitting instruments for controlling the flow of the positive and negative impulses over the line, each transmitting instrument being arranged to short-circuit the impulses of a given sign and frequency, and a series of receiving instruments each adapted to receive impulses of a given sign and frequency, substantially as set forth.

8. In a system of electrical communication, the combination with a main line, of two or more generators connected in series and generating alternating currents of different frequencies, means for controlling the passage of the positive and negative impulses from each generator over the line, a transmitting instrument for each set of impulses of a given sign and frequency, and a series of receiving instruments connected in parallel and each arranged to receive impulses of a given sign and frequency, substantially as set forth.

9. In a system of electrical communication, the combination with a main line, of two or more generators connected in series and generating alternating currents of different frequencies,branch circuits connected across the terminals of each generator, means located in each branch for controlling the passage of the positive and negative impulses from each generator over the line, transmitting instruments in each branch, and a series of receiving instruments connected in parallel and each arrangedto receive impulses of a given sign and frequency, substantially as set forth.

This specification signed and witnessed this 17th day of May, 1897.

LEO WALTER HILDBURGII.

Vitnesses:

W. P. IZEN, J NO. R. TAYLOR. 

